The present invention relates generally to transducers for ultrasound imaging systems and, more particularly, to dynamically configurable transducers for such systems.
Recently, substantial attention has been directed toward the development and implementation of internal and external ultrasound imaging systems.
Intraluminal, intracavity, intravascular, and intracardiac treatment and diagnosis of medical conditions utilizing minimally invasive procedures is an effective tool in many areas of medical practice. These procedures typically are performed using imaging and treatment catheters that are inserted percutaneously into the body and into an accessible vessel, such as the femoral artery, of the vascular system at a site remote from a region of the body to be diagnosed and/or treated. The catheter then is advanced through the vessels of the vascular system to the region of the body to be diagnosed and/or treated, such as a vessel or an organ. The catheter may be equipped with an imaging device, typically an ultrasound imaging device, which is used to locate and diagnose a diseased portion of the body, such as a stenosed region of an artery.
Intravascular imaging systems having ultrasound imaging capabilities generally are known. For example, U.S. Pat. No. 4,951,677, issued to Crowley, the disclosure of which is incorporated herein by reference, describes such an intravascular ultrasound imaging system. An ultrasound imaging system typically contains some type of control system, a drive shaft, and a transducer assembly including an ultrasound transducer. The transducer assembly includes a transducer element and is coupled to the control system by the drive shaft. The drive shaft typically includes an electrical cable, such as coaxial cable, for providing electrical communication between the control system and the ultrasound transducer.
In operation, the drive shaft and the transducer assembly are inserted, usually within a catheter, into a patient""s body and may be positioned near a remote region of interest. To provide diagnostic scans of the remote region of interest within, for example, a coronary blood vessel, the ultrasound transducer may be positioned near or within the remote region of the patient""s body. Diagnostic scans are created when the control system alternately excites and allows sensing by the ultrasound transducer. The control system may direct the ultrasound transducer toward or away from an area of the remote region. When the ultrasound transducer is excited, a transmitting/receiving surface of the transducer element creates pressure waves in the bodily fluids surrounding the ultrasound transducer. The pressure waves then propagate through the fluids within the patent""s body and ultimately reach the region of interest, forming reflected pressure waves. The reflected pressure waves then return through the fluids within the patient""s body to the transmitting/receiving surface of the transducer element, inducing electrical signals within the transducer element. The control system then may collect the induced electrical signals and may reposition the ultrasound transducer to an adjacent area within the remote region of the patient""s body, again exciting and sensing the transducer element. This process may continue until the remote region has been examined sufficiently and a series of induced signals has been collected. The control system then may process the series of induced signals to derive a diagnostic scan and may display a complete image of the diagnostic scan.
Those skilled in the art will appreciate that the type of transducer that may be required, or preferred, for a particular procedure often will vary depending upon the type of procedure to be performed. For example, for some procedures it may be desirable to utilize a transducer with a long, or extended focus, such that areas of tissue remote from the transducer may be imaged clearly, whereas in other procedures it may be desirable to utilize a transducer with a relatively short focus to image, for example, areas of tissue in relatively close proximity to the transducer. Those skilled in the art also will appreciate that, depending upon the type of procedure to be performed, it may be desirable to utilize transducers having the ability to implement certain scanning functions. Finally, those skilled in the art will appreciate that in many imaging systems, such as those described above, a transducer will be rotated to perform a scanning function, and that the provision of such capabilities may add significantly to the cost of an imaging system.
In view of the foregoing, it is believed that a need exists for an improved ultrasound transducer that overcomes the aforementioned obstacles and deficiencies of currently available ultrasound transducers. It is further believed that a need exists for a transducer that is dynamically configurable, such that its performance may be dynamically altered to meet the needs of a given application.
In one innovative aspect, the present invention is directed toward a dynamically configurable ultrasound transducer.
In one presently preferred embodiment, the transducer may comprise an array of capacitive transducer elements, a row decoder coupled to said array of capacitive transducer elements, a column decoder coupled to said array of capacitive transducer elements, a bias voltage source coupled to said row decoder, and a driving signal source coupled to said column decoder. Preferably, a master clock also is provided to allow for a synchronization of signals between the row decoder and column decoder.
Using the row decoder, a bias voltage may be applied to selected rows of capacitive transducer elements provided within the array to enable the function of those elements, and thereafter, a driving signal (or stimulus signal) may be supplied to selected columns of capacitive transducer elements provided within the array. In this fashion, numerous configurations of capacitive transducer elements may be activated for transmitting and receiving ultrasonic waves within a predetermined medium.
In another presently preferred embodiment, a dynamically configurable ultrasound transducer may comprise an array of capacitive transducer elements, a first pair of row and column decoders for applying a DC bias signal to selected capacitive transducer elements within the array, a second pair of row and column decoders for applying an AC driving signal to selected capacitive transducer elements within the array, and a clock for providing a master clock signal to the first and second pairs of row and column decoders.
Those skilled in the art will appreciate that different control circuits may be utilized within a dynamically configurable transducer in accordance with the present invention depending upon the performance characteristics needed from the transducer. For example, in alternative embodiments a DC bias signal by be applied to all of the capacitive transducer elements within an array, and a single row or column decoder could be utilized to selectively apply an AC driving signal to desired rows, or columns, with the array. Alternatively, a single row or column decoder circuit could be used to selectively couple both the DC bias signal and the AC driving signal to desired rows, or columns, of transducer elements within the array.
In another innovative aspect, the present invention is directed toward systems and methods for dynamically configuring an ultrasound transducer. Within such methods, a bias voltage, or a combination of a bias voltage and driving voltage, may be used to selectively activate and deactivate capacitive transducer elements provided within an array of such elements. Thus, using systems and methods in accordance with the present invention, it is possible to activate selected rows or columns of capacitive transducer elements in a predetermined sequence within a transducer element array or, alternatively, to enable and activate predetermined geometric configurations of the capacitive transducer elements within the array and in a predetermined sequence. Thus, those skilled in the art will appreciate that a dynamically configurable ultrasound transducer in accordance with the present invention may be configured in numerous ways, depending on a desired application or use of the transducer.
Other objects and features of the present invention will become apparent from consideration of the following description taken in conjunction with the accompanying drawings.